Kidney organogenesis is a complex process involving mesenchymal-epithelial transformation, branch morphogenesis and terminal differentiation. In the May 8 Proceedings of the National Academy of Sciences, Stuart et al. describe a microarray analysis of 8,740 rat genes during kidney development (Proc Natl Acad Sci USA 2001, 98:5649-5654). The authors developed data-analysis software for data equalization, statistical-significance testing and data mining. About 10% of genes were found to vary signi

The chromosomal region 17q23 is amplified in some cancer cells and is associated with poor prognosis for breast cancer. In the May 8 Proceedings of the National Academy of Sciences, Monni et al. describe the use of genomic and microarray analysis to characterize the 17q23 amplicon in breast cancer cells (Proc Natl Acad Sci USA 2001, 98:5711-5716). They constructed a 4 megabase contig covering the amplified region of chromosome 17, containing 17 genes and 26 expressed sequence tags (ESTs) identif

Pluripotent stem cells hold promise for transplantation therapy to treat degenerative diseases, but isolating a patient's stem cells may pose a technical limitation. In the April 27 Science, Wakayama et al. describe the application of cloning to generate embryonic stem (ES) cells (Science 2001, 292:740-743). The authors used nuclei from adult-derived somatic donor cells of five different strains of mice to produce cloned blastocysts. These were then used to derive 35 different nuclear transfer E

Sensitive PCR analysis of vaccine samples refutes the controversial hypothesis that the AIDS epidemic began with a contaminated oral polio vaccine.

The complex anatomical organization and cellular heterogeneity of the mammalian brain may complicate the interpretation of transcriptome analysis of brain tissues. In the April 24 Proceedings of the National Academy of Sciences, Zirlinger et al. describe how in situ hybridization studies can improve microarray analysis of the brain (Proc Natl Acad Sci USA 2001, 98:5270-5275). The authors compared the expression of over 34,000 genes using Affymetrix GeneChip oligonucleotide arrays with RNA from f

chick chimeras suggest that auditory perception in birds can be exchanged by brain transplantation.

There is no genetic evidence for filial cannibalism, in which parents eat their own offspring. In the April 24 Proceedings of the National Academy of Sciences, DeWoody et al. document filial cannibalism in fish in nature (Proc Natl Acad Sci USA 2001, 98:591-596). The authors captured male fish, of the tessellated darter and two sunfish species, and examined the cannibalized contents of the stomachs of nest-guarding males by polymorphic microsatellite marker analysis. They found that 10 out of 11

The genes that regulate circadian rhythms have been genetically characterized in flies and mice. In the April issue of EMBO Reports, Ebisawa et al. describe a screen for genetic polymorphisms associated with human circadian rhythm disorders (EMBO Reports 2001, 2:342-346). They performed a PCR-based analysis of the human period3 gene (hPer3), a homolog of a Drosophila clock gene, and identified 20 sequence variations, of which six predicted amino acid changes. Ebisawa et al. defined four haplotyp

now a candidate receptor gene has been identified.

There is evidence for substantial transfer of mitochondrial DNA (mtDNA) to the nuclear genome in plants. Analysis of the recently completed Arabidopsis thaliana genome sequence indicated a mtDNA insertion of 270 kilobases (kb), larger than previously described mitochondria-to-nuclear DNA insertions. In the April 24 Proceedings of the National Academy of Sciences, Stupar et al present a detailed cytological characterization of the mtDNA insertion in chromosome 2 of A. thaliana (Proc Natl Acad Sci

The importance of the INK4A/CDKN2A locus, encoding the p16/INK4a and p19/ARF proteins, in tumor suppression is underscored by the high frequency of mutation or silencing of the locus in human tumors. In the April 24 Proceedings of the National Academy of Sciences, Magdinier and Wolffe describe the role of the methyl-CpG binding protein MBD2 in INK4a/ARF gene repression in cancer cells (Proc Natl Acad Sci USA 2001, 98:4990-4995). They used chromatin immunoprecipitation (ChIP) experiments to study

Mammalian circadian clocks are regulated by a series of interacting positive and negative transcription-translation feedback loops in the hypothalamic suprachiasmatic nucleus (SCN). In the April 13 Science, Yagita et al. describe an in vitro model system that resembles the molecular oscillator in the SCN (Science 2001, 292:278-281). Cultured fibroblasts exhibit cycling circadian gene expression when stimulated with the vasocontracting peptide endothelin-1. Endothelin-1 induced cycling phases of